Electrical terminal structure with wedged conductor

ABSTRACT

A terminating structure in which a tight mechanical grip on a conductor is achieved by wedging the conductor in a hole which is at a slight angle to the vertical tapped hole for a set screw. The screw may be self tapping. The holes are preferably in the front of the terminating structure and in a position where the conductors can be inserted in a straight or almost straight position without having to bend the conductor. The structure can be fabricated from a stamped blank of metal.

United States Patent Robinson et al.

[451 Dec. 26, 1972 ELECTRICAL TERMINAL STRUCTURE WITH WEDGED CONDUCTORAssignee:

Filed:

Appl. No.: 132,295

Inventors: Daniel E. Robinson, Metuchen;

Solomon Rubinstein, Fanwood, both of NJ.

General Cable Corporation, New

York, N.Y.

April 8, 1971 US. Cl. ..339/198 R, 339/95 R, 339/242,

Int. Cl. ..II0lr 9/00 Field of Search ..339/l9, 22, 198, 242, 95, 96,

References Cited UNITED STATES PATENTS Clark ..339/97 P Stanback et a1.Downs et al....

Broch ....339/97 Lescarboura ..339/204 FOREIGN PATENTS OR APPLICATIONS455,722 2/1928 Germany ..339/272 R 941,204 4/1956 Germany ..339/272 ROTHER PUBLICATIONS M. C. Panaro, Self Locking Terminal 11-960 IBM Tech.Disc.

Primary Examiner-Marvin A. Champion Assistant Examiner-Robert A. I-IaferAttorney-Sandoe, I-Iopgood & Calimafde [57] ABSTRACT A terminatingstructure in which a tight mechanical grip on a conductor is achieved bywedging the conductor in a hole which is at a slight angle to thevertical tapped hole for a set screw. The screw may be self tapping. Theholes are preferably in the front of the terminating structure and in aposition where the conductors can be inserted in a straight or almoststraight position without having to bend the conductor. The structurecan be fabricated from a stamped blank of metal.

14 Claims, 10 Drawing Figures PATENTED DEC 2 6 I972 INVENTORS 9% BY, 2

ATTORNE YS.

ELECTRICAL TERMINAL STRUCTURE WITH WEDGED CONDUCTOR BACKGROUND ANDSUMMARY OF THE INVENTION This invention relates to a new and improvedtype of electrical terminating structure. Its main feature is that theconductor is inserted in the front of the terminating structure and inan almost straight position without having to make any bends. Thisbecomes particularly convenient when making electrical terminationswhere space is at a premium such as in junction boxes or in crowdedelectrical panels and switchboards.

With present types of terminating structures having a tunnel type ofterminating means, the conductor is usually bent at a right angle beforeinserting it in a hole or under a tab near the bottom of the terminatingstructure. Often the hole or tab must be probed for when the conductorentry locations are not readily accessible because of crowdedconditions. With other types of terminating bars, the conductor is bentin a loop before it is clamped by the head of a binding screw.

In this new type of terminating structure, a tight mechanical grip onthe conductor is achieved by wedging the conductor in a hole which is ata slight angle to the vertical tapped hole for the tightening screw. Thebar may be of copper, brass or aluminum. When using an aluminum bar itmay be plated with a suitable metal for corrosion prevention and forimproved electrical performance especially for terminating aluminumconductors. The terminating structure may be fabricated from rolledstock or it may be die cast. The holes may be drilled, punched or cast.The tightening screws may be brass or steel. A steel screw may be of aself tapping type when using an aluminum structure.

Included in the scope of this invention is a structure which isfabricated from a stamped strip or bland; preferably one of brass. Thestrip is bent to a configuration that has the same basic features as forthe machined terminal structure. Variations to achieve the basicconstruction can be employed. For example:

a. The tightening screw may be held by a rivetted tapped insert ratherthan in a pierced threaded hole.

b. The side supports for the conductor and for the tightening screw maybe of separate bent strips, which are either welded or rivetted inposition rather than an integral part of the terminal structure.

Other objects, features and advantages of the invention will appear orbe pointed out as the description proceeds.

BRIEF DESCRIPTION OF DRAWING In the drawing, forming a part hereof, inwhich like reference characters indicate corresponding parts in all theviews;

FIG. 1 is a sectional view showing a terminating structure made inaccordance with this invention and located in an enclosing housing orcontainer made of electrical insulating material;

FIG. 2 is a fragmentary top plan view of the terminating structure shownin FIG. 1 with the conductor and set screw removed;

FIG. 3 is a view similar to FIG. 1 but showing a modified form of theinvention in which the terminating structure is a hollow housing whichcan be made from a metal stamping and without any container;

FIG. 4 is a fragmentary sectional view taken on the line 4-4 of FIG. 3;

FIG. 5 is a fragmentary detailed view taken on the line 5-5 of FIG. 3;

5 FIG. 6 is a view similar to FIG. 3 but showing still another modifiedform of the invention;

FIGS. 7 and 8 are fragmentary views taken on the lines 7-7 and 8-8,respectively, of FIG. 6;

FIG. 9 is a fragmentary detailed view showing a modified constructionfor connecting together the edges of the stamping shown in FIG. 6; and

FIG. 10 is a fragmentary detailed view taken on the line 10-10 of figure9.

DESCRIPTION OF PREFERRED EMBODIMENT FIG. 1 shows a terminating structure16 which is located in a housing or container 18 preferably made ofelectrical insulating material. The housing or container 18 is open atone side which for purposes of the description can be considered thefront of the container 18 though this front is located at the top of thedrawing in FIG. 1. The opening exposes the front surface of theterminating structure 16. There is a well 20 in the back or bottom wallof the container 18. A shoulder 22 extending around the circumference ofthe well 20 provides a stop which limits the extent to which theterminating structure 16 can be inserted into the container.

In the front (top) wall of the structure 16, there are two holes oropenings including an unthreaded opening 26 for receiving a conductor 28of a power cable, and a threaded opening 30 into which a set screw 32fits. The opening 26 has a countersink 34 at its upper end to facilitatethe original entry of the conductor 28 into the opening 26. At the frontsurface of the structure 16, the openings 26 and 30 are spaced from oneanother; but they converge as they extend into the structure 16 andtoward the rearward (bottom) surface of the structure 16. The openings26 and 30 meet within the structure and when a conductor 28 is insertedas shown, the set screw 32 engages and clamps the conductor 28 tightlyagainst the wall of the opening 26 which is opposite the set screw 32.

With a steel set screw and a soft conductor 28 such as aluminum, thethreads of the set screw cut into the surface of the conductor 28 sothat the conductor is not only held in the structure 16 by friction butis also locked in the structure by the threads of the set screw 32. I Inthe construction shown in FIG. I, the well 20 is located in a positionat the back of the structure 16 so that the conductor 28 can extend somedistance beyond the structure 16, the depth of the well 20 determiningthe extent to which the conductor can extend beyond the structure 16. Byhaving the housing or container 18 made of electrical insulatingmaterial, the terminating structure 16 is protected from accidentalcontact on all sides except the front where the conductor 28 extendsinto the structure 16 and where the set screw 32 extends into thestructure to clamp the conductor.

The structure 16 can be of any desired length and FIG. 2 is a view ofthe front surface, indicated by the reference character 38 of thestructure 16. This view shows three openings 30 located at closelyspaced regions along the length of the structure 16. There are threecorresponding openings 26 for the openings 30; and it will be understoodthat the structure can be made of any desired length with as many pairsof openings 26 and 30 as there are conductors to be terminated. Theinsulating wall of the container 18 extends lengthwise of the structureand if desired can extend across the both ends of the structure.

FIG. 3 shows another form of the invention in which a hollow terminatingstructure 16a is used in place of the solid structure 16 shown inFIG. 1. The advantage of the construction shown in FIG. 3 is that it canbe made from a metal stamping and can, therefore, be much lighter andless expensive than the structure shown in FIG. 1. The principle of theconstruction shown in FIG. 3 is similar to that shown in FIG. 1 butcertain modifications in the construction are necessary because of thehollow interior.

A front wall 38a in FIG. 3 has an opening 26a for receiving a conductor28a of a power cable; and also has an opening 30a for receiving a setscrew 32a which threads into the opening 30a. I

The terminating structure 16a can be formed from a strip of metal whichis stamped to provide the openings 26a and 30a; and these opening arepreferably made by displacing metal from the portion of the wall wherethe opening is to be formed so that instead of an opening of thethickness of the metal, there is a longer opening formed by what is ineffect a drawing down of the metal so that what was the outside surfaceof the stamping becomes part of the inside surface of the opening 26aand 30a.

At the time that the openings 26a and 30a are stamped, other openingsare stamped as shown in FIG. 4. Theseinclude an opening 40 which isformed by displacing a strip or tab 42 from the wall of the stamping anda corresponding opening 40' formed by displacing another strip or tab42'. At another location,'openings 44 and 44 are formed by displacingtabs 46 and 46.

The purpose of the tabs 42, 42, 46 and 46' will be apparent by comparingFIGS. 3 and 4. The tabs 42 and 42 form in effect side surfaces for theopening into which the conductor 28a extends. Thus'contact with thesetabs 42 and 42' gives the conductor 28a a long surface for holding it inalignment with the opening 26a and for holding it out of contact withthe wall 48 immediately behind it. Thus the conductor 28a is wedged intowhat amounts to a modified VEE bracket that holds the conductor 28a in acentered position and prevents it from rolling to either side whenclamped by the set screw 32a.

Likewise the tabs 46 provide a pair of side walls against which the setscrew 32a contacts to hold it centered in alignment with the opening 30aand to prevent it from shifting to either side when it contacts with theconductor 28a in the lower or backward part of the terminating structure160.

After the openings 26a and 30a, and the openings 40, 40, 44 and 44' havebeen formed in the stamping, together with other spaced openings 50 andspaced edge tabs 52, the stamping is bent to form the terminatingstructure shown in FIG. 3. It is bent at two corners 54 and 56 at theback (bottom) of the terminal structure and it is bent outward along aline 58 to increase the width of the front surface of the terminatingstructure. The stamping is also bent around an arc of about 135 alongthe line 60 and is then bent at a location between the openings 26a and30a to bring the edge with the openings 50 adjacent to the opposite edgewith the edge tabs 52. The edge tabs 52 are inserted through theopenings 50 and then bent over as shown in FIG. 5, to hold the variousparts of the terminating structure in the intended relation shown inFIG. 3.

FIGS. 6, 7 and 8 show a construction which is similar to that shown inFIGS. 3, 4 and except that an opening 64 in one wall produces tabs 66and 66' which extend in different planes to the tabs 46 and 46' of FIGS.

3 and 4. The purpose of the tabs 66 and 66 is essen-' tially the samebut they have the advantage that they can be used to hold the set screw32b further away from the adjacent wall of the terminating structure andthereby bring the set screw closer to the opposite wall against whichthe conductor 28b is clamped. This permits the terminating structure tobe used with a conductor of smaller diameter than could be used in theconstruction of FIG. 3. It also permits the tabs 66 and 66 to bethreaded, if desired.

' Another difference in the construction shown in FIG. 6, as compared tothat of FIG. 3 is that there are openings 70 formed in a different wallof the stamping as compared to that of FIG. 3 and there are tabs 72formed along the opposite edge of the stamping for insertion through theedge openings 70 as shown in FIG.

The terminating structures shown in FIGS. 3 8 are similar to the oneshown in FIGS. 1 and 2 in that they have substantial longitudinal extentwith as many conductor-receiving openings 26a or 26!) as desired and acorresponding number of openings 30a and 30b for receiving screws toclamp the conductors in the terminating structures. There may be as manyholes or openings 50 and 70 along the edge of the stamping as there areset screw holes or there may be more or fewer depending upon thestiffness of the material and upon how many points of connection betweenthe edges that are necessary to maintain the shape of the terminatingstructure. In place of the tabs 52 and 72 for anchoring the oppositeedge of the stamping at the openings 50 and 70, other means can beemployed for connecting the edges together at the corner where theoriginal free edges of the stamping are brought together after bendingthe terminating structure at enough places to form a closed product orclosed perimeter. These means include various seaming processes,welding, soldering or any other well known method of connecting edges ofmetal parts together.

FIG. 9 shows a construction similar to FIG. 6 but with longer tabs 76 inplace of the tabs 72 of FIG. 6. These longer tabs 76 extend throughopenings 70c and because of the greater length of these tabs 76 they canbe bent around the front and down the opposite side of the wall throughwhich the openings 700 are punched. This provides a somewhat strongerconnection than that shown in FIG. 6, but one that requires morematerial. Other parts in FIG. 9 corresponding with those in FIG. 6 areindicated by the same reference character with the letter 0 appended inplace of the letter b of FIG. 6.

The preferred embodiment of the invention has been illustrated anddescribed, but changes and modifications can be made and some featurescan be used in different combinations without departing from theinvention as defined in the claims.

What is claimed is:

1. A terminating structure comprising a body portion made of metal whichis a good conductor of electricity, the structure having a plurality ofspaced openings therein opening through the front surface thereof forreceiving conductors that are to be connected with the structure, asurface within the terminating structure in alignment with and extendinggenerally parallel to the longitudinal axis of the opening and formingin effect a continuation of a side of said opening for contact with theconductor and set screws extending through the front face of theterminating structure in directions to intersect the space occupied bythe respective conductors that are in contact with the axially extendingsurfaces for clamping the conductors against said surfaces,characterized by each set screw having a tapered portion of its lengthnear the lower end of the set screw with a tapered surface that wedgesthe conductor against the axially extending surface with which a side ofthe conductor contacts.

2. The terminating structure described in claim 1 characterized by therebeing a separate set screw for each of the openings, each set screwextending through a tapped opening having its longitudinal axis at anacute angle to the longitudinal axis of the opening into which theconductor extends, said acute angle being less than 22%.

3. The terminating structure described in claim 1 characterized by theset screw opening being spaced from the conductor-receiving opening atthe surface of the structure, but the axes of the openings converging atan acute angle and intersecting one another within the structure, theacute angle between themes of the set screw openings and the conductoropenings being between and 22 /z.

4. The terminating structure described in claim 1 characterized by eachset screw having threads on a portion of its outside surface in positionto cut threads in a side of the conductor in the conductor-receivingopening.

5. The terminating structure described in claim 1 characterized by saidstructure being enclosed in a housing that is made of electricalinsulating material and that is open on only one side, and the frontsurface of the structure being exposed from the open side of thehousing, and both the conductor-receiving openings and openings for theset screws opening through said front surface, each conductor-receivingopening and its associated set screw opening being spaced from oneanother where they open through the front surface of the bar butconverging as they extend into the bar.

6. The terminating structure described in claim 5 characterized by eachset screw being substantially larger in cross-section than theconductor.

7. The terminating structure described in claim 5 characterized by thehousing having a well beyond the back surface of the structure, ashoulder around the well limiting the extent to which the structure canbe inserted into the housing, each of the openings for a conductor andits associated set screw coming together in said structure and openingthrough the back surface of said structure into communication with thewell whereby the conductor can be extended beyond the back surface ofthe structure for a distance equal to the depth of the well.

8. The terminating structure described in claim 1 characterized by thestructure being a hollow housing with a front wall through which theconductor-receiving openings open, and threaded openings in the housingfor the set screws, each conductor contacting with its set screw withinthe hollow housing, an interior thrust surface of the housing includingthe axially-extending surface that contacts with one side of theconductor and that is spaced away from the screw, and an interior thrustsurface of the housing that contacts with the side of the screw that isaway from the conductor.

9. A terminating structure comprising a body portion made of metal whichisa good conductor of electricity, a front surface of the body portionwith a plurality of spaced openings in the structure and opening throughthe front surface thereof for receiving conductors that are to beconnected with the structure, and set screws that clamp the conductorsin the openings, characterized by the structure being a hollow housingwith a front wall through which the conductor-receiving openings open,and threaded openings in the housing for the set screws, each conductorcontacting with its set screw within the hollow housing, an interiorthrust surface of the housing that contacts with one side of theconductor that is away from the screw, and an interior thrust surface ofthe housing that contacts with the side of the screw that is away fromthe conductor, and further characterized by the housing being a stampedstrip which is bent along ,an axis extending lengthwise of the structureto provide a front wall, longitudinal side walls and a back wall, thethrust surfaces within the housing being strips that connect withopposite side walls of the housing and that hold the conductors andscrews out of the plane of the side walls and in contact with eachother.

10. The terminating structure described in claim 9 characterized by thestrips being of one piece construction with the rest of said walls ofthe housing and being formed of material displaced inwardly at an anglefrom the sides of the housing.

11. The terminating structure described in claim 9 characterized by eachof the strips having walls that converge toward the side of the housingin which said strip is connected, the convergence of the conductorcontacting surfaces being toward axes that extend generally parallel tothe direction of extent of the conductors, and the convergence of thescrew contacting surfaces being toward axis that extend generallyparallel to the direction of extent of the screws.

12. The terminating structure described in claim 9 characterized by someof the thrust surfaces being on tabs that connect with one wall of thehousing and that are spaced from one another lengthwise of thefront-toback extent of the said wall and that are substantially normalat their inner end portions to the side wall with which they areconnected, and their thrust surfaces being arcuate about an axis ofcurvature that is generally parallel to the side wall to which the tabsare connected.

13. The terminating structure described in claim 9 characterized by thehousing being formed from a blank that is bent at the junctures of thefront, side and back walls with one another, one of the junctures beingat the longitudinal edges of the blank, andsaid edges being connectedtogether by tabs at one edge projecting through openings in the oppositeedge.

1. A terminating structure comprising a body portion made of metal whichis a good conductor of electricity, the structure having a plurality ofspaced openings therein opening through the front surface thereof forreceiving conductors that are to be connected with the structure, asurface within the terminating structure in alignment with and extendinggenerally parallel to the longitudinal axis of the opening and formingin effect a continuation of a side of said opening for contact with theconductor and set screws extending through the front face of theterminating structure in directions to intersect the space occupied bythe respective conductors that are in contact with the axially extendingsurfaces for clamping the conductors against said surfaces,characterized by each set screw having a tapered portion of its lengthnear the lower end of the set screw with a tapered surface that wedgesthe conductor against the axially extending surface with which a side ofthe conductor contacts.
 2. The terminating structure described in claim1 characterized by there being a separate set screw for each of theopenings, each set screw extending through a tapped opening having itslongitudinal axis at an acute angle to the longitudinal axis of theopening into which the conductor extends, said acute angle being lessthan 22 1/2 *.
 3. The terminating structure described in claim 1characterized by the set screw opening being spaced from theconductor-receiving opening at the surface of the structure, but theaxes of the openings converging at an acute angle and intersecting oneanother within the structure, the acute angle between the axes of theset screw openings and the conductor openings being between 10* and 221/2 *.
 4. The terminating structure described in claim 1 characterizedby each set screw having threads on a portion of its outside surface inposition to cut threads in a side of the conductor in theconductor-receiving opening.
 5. The terminating structure described inclaim 1 characterized by said structure being enclosed in a housing thatis made of electrical insulating material and that is open on only oneside, and the front surface of the structure being exposed from the openside of the housing, and both the conductor-receiving openings andopenings for the set screws opening through said front surface, eachconductor-receiving opening and its associated set screw opening beingspaced from one another where they open through the front surface of thebar but converging as they extend into the bar.
 6. The terminatingstructure described in claim 5 characterized by each set screw beingsubstantially larger in cross-section than the conductor.
 7. Theterminating structure described in claim 5 characterized by the housinghaving a well beyond the back surface of the structure, a shoulderaround the well limiting the extent to which the structure can beinserted into the housing, each of the openings for a conductor and itsassociated set screw coming together in said structure and openingthrough the back surface of said structure into communication with thewell whereby the conductor can be extended beyond the back surface ofthe structure for a distance equal to the depth of the well.
 8. Theterminating structure described in claim 1 characterized by thestructure being a hollow housing with a front wall through which theconductor-receiving openings open, and threaded openings in the housingfor the set screws, each conductor contacting with its set screw withinthe hollow housing, an interior thrust surface of the housing includingthe axially-extending surface that contacts with one side of theconductor and that is spaced away from the screw, and an interior thrustsurface of the housing that contacts with the side of the screw that isaway from the conductor.
 9. A terminating structure comprising a bodyportion made of metal which is a good conductor of electricity, a frontsurface of the body portion with a plurality of spaced openings in thestructure and opening through the front surface thereof for receivingconductors that are to be connected with the structure, and set screwsthat clamp the conductors in the openings, characterized by thestructure being a hollow housing with a front wall through which theconductor-receiving openings open, and threaded openings in the housingfor the set screws, each conductor contacting with its set screw withinthe hollow housing, an interior thrust surface of the housing thatcontacts with one side of the conductor that is away from the screw, andan interior thrust surface of the housing that contacts with the side ofthe screw that is away from the conductor, and further characterized bythe housing being a stamped strip which is bent along an axis extendinglengthwise of the structure to provide a front wall, longitudinal sidewalls and a back wall, the thrust surfaces within the housing beingstrips that connect with opposite side walls of the housing and thathold the conductors and screws out of the plane of the side walls and incontact with each other.
 10. The terminating structure described inclaim 9 characterized by the strips being of one piece construction withthe rest of said walls of the housing and being formed of materialdisplaced inwardly at an angle from the sides of The housing.
 11. Theterminating structure described in claim 9 characterized by each of thestrips having walls that converge toward the side of the housing inwhich said strip is connected, the convergence of the conductorcontacting surfaces being toward axes that extend generally parallel tothe direction of extent of the conductors, and the convergence of thescrew contacting surfaces being toward axis that extend generallyparallel to the direction of extent of the screws.
 12. The terminatingstructure described in claim 9 characterized by some of the thrustsurfaces being on tabs that connect with one wall of the housing andthat are spaced from one another lengthwise of the front-to-back extentof the said wall and that are substantially normal at their inner endportions to the side wall with which they are connected, and theirthrust surfaces being arcuate about an axis of curvature that isgenerally parallel to the side wall to which the tabs are connected. 13.The terminating structure described in claim 9 characterized by thehousing being formed from a blank that is bent at the junctures of thefront, side and back walls with one another, one of the junctures beingat the longitudinal edges of the blank, and said edges being connectedtogether by tabs at one edge projecting through openings in the oppositeedge.
 14. The terminating structure described in claim 9 characterizedby the conductor-receiving openings and set screw openings being in thefront wall of the housing, and the wall material being displacedinwardly around each of the openings to give the wall a greatereffective thickness around the edges of the openings.